The present invention relates to a photosensitive pressure sensitive image recording medium in which an immense numbers of microcapsules are carried on a substrate, the microcapsules encapsulating therein dye precursor and polymerizable compound, etc. More particularly, the invention relates to a thermal developing type photosensitive pressure sensitive image recording medium in which a latent image is formed in a microcapsules layer by changing mechanical strength of the microcapsules upon photopolymerization, and an output image corresponding to the latent image is formed on an image receiving sheet by transferring the dye precursor etc. thereon by virtue of rupture of the microcapsules upon pressure application.
Conventional photosensitive pressure sensitive image recording medium is described in Japanese Patent Application Kokai (OPI) Nos. 58-88739, 59-30537 and 59-137944, In an image forming techniques described in these publications, at least two components initially separated from each other are reacted with each other because of a change in physical parameters such as pressure change and temperature change. The reaction accompanies optical change in, for example, light absorbing spectrum range and light absorbing intensity. Thus, an image recording operation can be made dependent on the change in the physical parameters.
According to one typical conventional example, a photosensitive pressure sensitive image recording medium is provided in which an immense numbers of microcapsules are carried on a substrate. Mechanical strength or hardness of the microcapsules are changed upon light irradiation. Further, a developer medium is provided in which a developing agent is coated on a base substrate. The microcapsule layer and the developer layer are superposed with each other for pressure developing operation. As a result, microcapsules are selectively ruptured depending on their hardness, so that dye or dye precursor and dye receiver or developing agent are reacted with each other for forming a visible output image on the developer sheet.
Further, a conventional thermal developing type photosensitive pressure sensitive image recording medium is disclosed in Japanese Patent Application Kokai (OPI) Nos. 61-275742 and 61-278848. This type of recording medium has a substrate coated with microcapsules encapsulating therein photosensitive silver halide, reducing agent, polymerizable compound and color former. Image exposure operation is performed with respect to the recording medium, and then the medium is heated so as to provide reaction of the polymerizable compound, to thereby provide difference in mechanical strength among the microcapsules. Next, an image receiving sheet capable of allowing the color former to be easily transferred is superposed with the image recording medium, and these are pressed together for selectively rupturing the microcapsules. As a result, the color former is transferred onto the image receiving medium for obtaining an output color image.
The image receiving medium or sheet must undergo special treatment for receiving the output image thereon. And the receiving medium is formed with an image receiving layer which is a glossy layer for obtaining a glossy output image. However, the gloss surface also has disadvantage in that the output image cannot be easily recognized due to visible light reflection thereat, and further, it would be rather difficult to manually write words or illustrations onto the glossy layer, i.e., writing performance may be degraded if the writing surface has the glossy layer.